Steve Back’s work might look like a series of Rothko paintings, but they are, in fact, stunning pictures of algae. Hutt Lagoon is a Western Australian salt lake that contains the world’s largest system of algae farms; they get their bright hues from algae that secrete many colored substances, especially beta-carotene, which is commonly used as red food coloring.

An architectural photographer, Back was on assignment in the area when he first became interested in photographing the algae. He rented a small aircraft and headed southwest for the islands off the coast. While flying over the lagoon he was struck by the beauty and symmetry of one particular farm just south of Kalbarri.

“I had seen the lakes from ground level and they are actually quite unimpressive – you just see the muddy foreshore with lots of crystallites,” Back tells TIME, speaking from Australia.

But the view was clearly different from the air. Drawing on his architectural roots, Back was drawn to the composition and form. “As I get older I’m much more interested in the purer expression of line and form,” says Back.

The man-made pens in the middle of the lake play off each other, he adds, and the texture and lines trick the viewer into believing they are looking at a painting: “People don’t know what they are looking at,” says Back. “It invites the viewer to stop for a moment and ask what is actually going on.”

Steve Back is an architectural and interiors photographer living in Sydney, Australia.